Tooth formation and arrangement for rotary drilling



1%, 19320 g, 5, gg 1,?Hfi3 TOOTH FORMATION AND ARRANGEMENT FOR ROTARYDRILLING Filed Dec. 10, 1930 INVENTOR.

' Clarence E. Reed A TTORNE Y.

Patented Aug. 16, 1932 UNITED STATES PATENT OFFICE .CLARENCE E. REED, OFWICHITA, KANSAS, ASSIGNOR TO CHICAGO PNEUMATIC TOOL COMPANY, OF NEWYORK, N. Y., A CORPORATION OF NEW JERSEY TOOTH FORMATION AND ARRANGEMENTFOR ROTARY DRILLING Application filed December 10, 1930. Serial No.501,169.

This invention relates to apparatus for rotary drilling. Morespecifically it relates to the formation and arrangement of cuttingteeth including the method of forming the same. WVhile the toothformation has features of general application it has been developed withparticular relation to rollencutters for deep well drilling, especiallythe socalled cone cutters and in the detailed descrip tion attentionwill be confined to this type of cutter.

In its more specific aspect, the invention relates to the large teethformed on roller cutters of frustoconical shape to adapt the same togeneral purpose drilling of all formations encountered and not to hardrock only. As heretofore made cone cutters have had annular concentricrows of inverted V or Wedge shaped teeth, the broad slopes and wide edgeof which set up resistance to penetration into the earth formation andthe material displaced by the rolling edge moves into the groove betweenthe edges and becomes packed hard and solid by the weight of the drill.This displaced material interferes with and makes impossible deeppenetration by the edge even to the nominal length of the tooth becausethe material wedged into the bottom of the groove forms a stop tofurther penetration. Since the grooves between the teeth are shallow,the displaced. earth material becomes so tightly wedged and packedtherein as a result of frictional contact with the bottom of the holethat when the tooth has rolled under the stream of flushing fluid, thelatter does not always and uniformly remove the packed material. This isparticularly true in shales and sticky formations where it is notuncommon to encounter a. condition in which the adhering materialobliterates all the groovesbetween the teeth and between the rows ofteeth, which condition is commonly referred to as balling up. In such acondition the,

cones -will no longer roll and are soon worn fiat on one side anddestroyed.

- Some of the teeth at the heel of a cone must contactwith the side ofthe hole as it is drilled 'a nd: the cutting edge of the tooth must bebacked up'with sufiicient material to take care of wear if a uniformhole diameter is to be maintained. In conical cutters having inverted Vor wedge .type teeth so much metal is leftat the heel that excessivefriction results which hinders rapid penetration into the earthformation unless the cutter is tipped to an angle which gives not muchmore than a mere point contact at the side or heel. However, ifpenetration is secured by such an expedient, the point contact at theheel is soon ground off and the diameter of the drill hole reduced. Thisis disastrous in well digging since it requires dangerous reaming.

An attempt has been made to obtain maximum flushing efiiciency and toavoid the above tion may be very rapid when there is consider-r ableabrasive material in the flushing stream; the slabbing off of the baseof the cone further removes most of the material which is necessar tomaintain the gauge of the hole.

ne object of the invention is to provide an improved tooth formationrforroller cutters which will increase footage, prolong'the life of thecutters, and permit the same to perform work more efliciently andcheaply than previously known cutters. Another object is to avoid thedifliculties of previously known arrangements and. to secure theimproved results without sacrifice of ability on the part of the cuttersto maintain the gauge or diam eter of the'drill hole. Other objects willbe apparent from the detailed description which follows.

This invention provides increased clearance between the teeth bywidening and deepening the space between the cutting edges of the tooth.The tooth form is changed to a shape giving dee penetration under loadwithout the sacri cc of strength, this being effected by "shortening theslope contact of the wedge toot-hand providinga projecting base bycutting a groove between adjoining Wedge shaped teeth, thus removing aportion of the base of each. This not only gives clearancefor apenetrating cutting edge but also provldes greatly increased and amplespace for the displaced material to move into. The groove preferably hasparallel sides which in the case of a roller cutter has the effect ofslightly undercutting the base of the tooth so that the sides of thebase diverge slightly toward the wedge shaped cutting edge. Thus theshallow space between the adjoining wedge shaped teeth of the oldarrangement is much increased. by deepening the same and changing itsshape, thereby providing an area and a receptacle, so'to speak, for thedisplaced earth formation. The space thus provlded has more capacitythan the volume ofearth displaced by the cutting edge in one contact.With this large space the roll of the, edges will not cause the body ofthe cone under the weight of the bit to pack the displaced earth in thegroove so tightly and the shape of the groove will not permit the light-1y packed material to fall out but will serve as a bucket on a conveyerto carry it from the cutting face at the bottom of the hole into thepath of the axially directed flushing fluid in the bit body.- Theflushing fluid issuing under high pressuredirectly over the end of thegroove will clear the same thoroughly, with the .result that the groovepockets will pass down again into operating position clean and free toenable the tooth to enter deeply into the virgin formation. Theseuniquely shaped grooves between the wedge teeth remove so much metalfrom the heel of the cone that excessive friction at the side of thehole is largely eliminated without requiring a change in the angle ofthe cone but at the same time the contacting edge of the tooth issupported by metal of ample-width and length parallel to the side of thehole to tain the gauge of the latter.

In order to illustrate the invention, one concrete embodiment thereof isshown in the accompanying drawing in which: Fig. 1 is a verticalsectional view throng the lower end of a two cone bit head, the conecutters being shown in elevation;

V Fig. 2 is a vertical central sectional view flhrpiugh the cone shellon the left of the bit Fig. 3 is a rear or base plan view, partly brokenaway, of the cone shell shown'in. Fig. 2; and

. Fig. 4 is a greatly enlarged and elevational view of adjoining teethon the cutter, indicating in broken lines the former wedge formation ofthe teeth and, in full lines, the improved form of the presentinvention.

While the-tooth formation of the present invention may be used generallyand applied to roller cutters of any known or desired type used in bitheads of any form, I have illustrated in Fig. 1 a two cone bit head,cone cutters, and a supporting arrangement therefor disclosed in myissued Patent No. 1,636,666 and Reissue Patent No. 17,741. The cutterhead is indicated at 5 and is provided with an axially disposed washpipe 6 for flushing fluid which discharges parallel with and between thecutting faces of cone cutters 7 which are suitably supported by spindleand shank members 8 in the lower end of the bit head The conical surfaceof each of the cone cutters 7 is provided with annular concentric rows914 inclusive of inverted V or wedge shaped cutting teeth. From the heelor base end of each cone radial cuts 15 of considerable depthandslanting slightly toward the surface of the cone are cut through aportion of the same, such as the last two rows of teeth let-and 13. Eachof the cuts as shown is made with parallel sides between adjoining teethwith the result that a portion of the base of each tooth is removed asclearly indicated in the enlarged view (Fig. 4) where the broken line wshows the original cutting for the uniformly wedge shaped teeth and thefull lines therebeneath show the-groove 15 made by the additional cut.Grooves 15 are of sufiicient depth and width to form teeth 14a in rows14 and 13a in rows-13 into long penetrating teeth and to provide apocket for the displaced material. Inasmuch as the teeth are annularlyarranged and grooves 15 have parallel sides, the effect upon teeth 13aand 14a is to make the bases of the same slightly diverging outwardlytoward their wedge shaped cutting edges, this divergence being morepronounced in cones of small diameter than in cones of large diameter.

From the above it will be apparent that as cone 7 rolls intotheformation, the cutting teeth 13a and 14a near the heel of the conepenetrate deeply and by reason of the 'enlarged pockets formed bygrooves 15 the dislodged material is loosely pressed into the same,these pockets serving to hold the material as the teeth roll upwardlyuntil they come under the powerful stream of flushing fluid issuing fromwash pipe 6. There is minimum dispersion of the flushing fluid whichfully removes the loosely packed material in grooves 15 so that when theteeth again enter the formation the pockets are free and clear. It willalso be apparent that the considerable amount of material removed fromthe heel of the cone cutters by grooves 15 reduce friction on the sideof the hole but that ample metal is still left to back the cutting edgeof the teeth 14a so as to maintain the gauge of the hole.

While the invention has been herein disclosed as to its, method andapparatus aspects in what is now considered to beits, preferred form, itis to be understood that the invention is not limited to the specificdetails thereof but covers all changes, modifications, and adaptationswithin the scope of the appended claims.

I claim as my invention:

1. In rotary drilling apparatus for earth boring, a roller cutter havinglong penetrating teeth formed with a wedge shaped or inverted V pointand substantially parallel sides below said point, adjacent teeth beingspaced from one another to provide a pocket for the material displacedby the points of the teeth.

2. In rotary drilling apparatus for earth boring, a roller cutter havingspaced annular rows of cutting teeth, the teeth in each row being spacedfrom one another and having inverted V or wedge points and extendedbases with substantially parallel or slightly diverging sides towardsaid points.

3. In rotary drilling apparatus for earth boring, a cone cutter havingconcentric rows of inverted V or wedge shaped teeth, portions of thebases of adjacent teeth in certain of said rows being removed bytransverse cuts to extend the overall length of the teeth and to providepockets therebetween for the material displaced by the points of saidteeth.

4:. In rotary drilling apparatus for earth boring, a cone cutter havingconcentric rows of inverted V or wedge shaped teeth, portions of thebases of adjoining teeth in the base or heel rows having been removed byradial cuts between said teeth from the base of the cone to make longerteeth, to provide pockets for displaced material between the teeth, andto reduce the mass of metal in contact with the side of the drill holethereby to reduce friction without sacrificing metal necessary tomaintain the gauge of the hole.

5. In rotary drilling apparatus for earth boring, a cone cutter havingone or more rows of teeth separated by grooves extending along linesconverging at the apex of the cone, said grooves having substantiallyparallel side walls adjoining V-shaped walls on the teeth.

Signed by me at Wichita, in the county of Sedgwick and State of Kansas,this 6th day of December, 1930.

CLARENCE E. REED.

